1 /*
2 * linux/fs/ext4/symlink.c
3 *
4 * Only fast symlinks left here - the rest is done by generic code. AV, 1999
5 *
6 * Copyright (C) 1992, 1993, 1994, 1995
7 * Remy Card (card@masi.ibp.fr)
8 * Laboratoire MASI - Institut Blaise Pascal
9 * Universite Pierre et Marie Curie (Paris VI)
10 *
11 * from
12 *
13 * linux/fs/minix/symlink.c
14 *
15 * Copyright (C) 1991, 1992 Linus Torvalds
16 *
17 * ext4 symlink handling code
18 */
19
20 #include <linux/fs.h>
21 #include <linux/jbd2.h>
22 #include <linux/namei.h>
23 #include "ext4.h"
24 #include "xattr.h"
25
26 #ifdef CONFIG_EXT4_FS_ENCRYPTION
ext4_follow_link(struct dentry * dentry,struct nameidata * nd)27 static void *ext4_follow_link(struct dentry *dentry, struct nameidata *nd)
28 {
29 struct page *cpage = NULL;
30 char *caddr, *paddr = NULL;
31 struct ext4_str cstr, pstr;
32 struct inode *inode = dentry->d_inode;
33 struct ext4_encrypted_symlink_data *sd;
34 loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
35 int res;
36 u32 plen, max_size = inode->i_sb->s_blocksize;
37
38 if (!ext4_encrypted_inode(inode))
39 return page_follow_link_light(dentry, nd);
40
41 res = ext4_get_encryption_info(inode);
42 if (res)
43 return ERR_PTR(res);
44
45 if (ext4_inode_is_fast_symlink(inode)) {
46 caddr = (char *) EXT4_I(dentry->d_inode)->i_data;
47 max_size = sizeof(EXT4_I(dentry->d_inode)->i_data);
48 } else {
49 cpage = read_mapping_page(inode->i_mapping, 0, NULL);
50 if (IS_ERR(cpage))
51 return cpage;
52 caddr = kmap(cpage);
53 caddr[size] = 0;
54 }
55
56 /* Symlink is encrypted */
57 sd = (struct ext4_encrypted_symlink_data *)caddr;
58 cstr.name = sd->encrypted_path;
59 cstr.len = le32_to_cpu(sd->len);
60 if ((cstr.len +
61 sizeof(struct ext4_encrypted_symlink_data) - 1) >
62 max_size) {
63 /* Symlink data on the disk is corrupted */
64 res = -EIO;
65 goto errout;
66 }
67 plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ?
68 EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len;
69 paddr = kmalloc(plen + 1, GFP_NOFS);
70 if (!paddr) {
71 res = -ENOMEM;
72 goto errout;
73 }
74 pstr.name = paddr;
75 pstr.len = plen;
76 res = _ext4_fname_disk_to_usr(inode, NULL, &cstr, &pstr);
77 if (res < 0)
78 goto errout;
79 /* Null-terminate the name */
80 if (res <= plen)
81 paddr[res] = '\0';
82 nd_set_link(nd, paddr);
83 if (cpage) {
84 kunmap(cpage);
85 page_cache_release(cpage);
86 }
87 return NULL;
88 errout:
89 if (cpage) {
90 kunmap(cpage);
91 page_cache_release(cpage);
92 }
93 kfree(paddr);
94 return ERR_PTR(res);
95 }
96
ext4_put_link(struct dentry * dentry,struct nameidata * nd,void * cookie)97 static void ext4_put_link(struct dentry *dentry, struct nameidata *nd,
98 void *cookie)
99 {
100 struct page *page = cookie;
101
102 if (!page) {
103 kfree(nd_get_link(nd));
104 } else {
105 kunmap(page);
106 page_cache_release(page);
107 }
108 }
109 #endif
110
ext4_follow_fast_link(struct dentry * dentry,struct nameidata * nd)111 static void *ext4_follow_fast_link(struct dentry *dentry, struct nameidata *nd)
112 {
113 struct ext4_inode_info *ei = EXT4_I(dentry->d_inode);
114 nd_set_link(nd, (char *) ei->i_data);
115 return NULL;
116 }
117
118 const struct inode_operations ext4_symlink_inode_operations = {
119 .readlink = generic_readlink,
120 #ifdef CONFIG_EXT4_FS_ENCRYPTION
121 .follow_link = ext4_follow_link,
122 .put_link = ext4_put_link,
123 #else
124 .follow_link = page_follow_link_light,
125 .put_link = page_put_link,
126 #endif
127 .setattr = ext4_setattr,
128 .setxattr = generic_setxattr,
129 .getxattr = generic_getxattr,
130 .listxattr = ext4_listxattr,
131 .removexattr = generic_removexattr,
132 };
133
134 const struct inode_operations ext4_fast_symlink_inode_operations = {
135 .readlink = generic_readlink,
136 .follow_link = ext4_follow_fast_link,
137 .setattr = ext4_setattr,
138 .setxattr = generic_setxattr,
139 .getxattr = generic_getxattr,
140 .listxattr = ext4_listxattr,
141 .removexattr = generic_removexattr,
142 };
143